Water soluble films have previously been made from polyvinyl alcohol and vinyl acetate resin blends. These chemicals are generally not compatible with any number of chemical systems. For example, these polymers are generally not compatible with chemical systems having a high pH or alkalinity such as caustic (NaOH) or caustic type materials. The alkali reacts with the vinyl acetate portion of the film converting it to vinyl alcohol. Films made of 100 wt-% vinyl alcohol have dramatically reduced water solubility. Moreover, packaged chemical detergents, cleaners, and the like must also be contained in a system which combines strength and structural integrity with storage stability to contain the product during storage and transportation prior to reaching its final end use. At the final location the package has to have enough strength to withstand handling prior to use.
Finally, many chemical cleaners have a highly alkaline nature. As a result, operational handling of these compositions, especially in the environment of use, often creates definite hazards stemming from the premature creation of high pH solutions which may result in severe injury to the operator.
Prior attempts to solve these problems include Torimae, Japanese Patent Document No. 2,163,149 and 0,260,906 which disclose cold water soluble films resulting from a copolymer of itaconic acid and saponified vinyl acetate and modified polyvinyl alcohol films used for packaging solid detergents, respectively; Proctor & Gamble, Japanese Patent No. 2,155,999 which discloses water soluble packages containing liquid detergents, the film generally comprising a vinyl alcohol polymer; Albert, U.S. Pat. No. 3,892,905 which discloses films made of a polymer mixture of polyvinyl alcohol and polyvinyl pyrrolidone; and Japanese Patent No. 2,108,534 to Torimae discloses cold water soluble multi-layer films for powder detergent packaging generally comprising vinyl alcohol polymers.
However, while these publications disclose films which generally would be classified as water soluble, there is no discussion regarding the maintenance of water solubility in the face of solids or solutions having an alkaline pH. Moreover, these publications do not disclose the manner in which the solubility of the polymeric films can be controlled generally.
As a result, a need still exists for a package cleaning system which has a high structural integrity and remains alkaline stable, preventing exposure to the operator prior to use and remains aqueous soluble or dispersible even in the presence of, or after contact with highly alkaline solutions.